<!doctype html>
<!--
Copyright 2018 The Immersive Web Community Group

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-->
<html>
  <head>
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
    <meta name='mobile-web-app-capable' content='yes'>
    <meta name='apple-mobile-web-app-capable' content='yes'>

    <!-- Origin Trial Token, feature = WebXR Device API, origin = https://immersive-web.github.io, expires = 2018-08-28 -->
<meta http-equiv="origin-trial" data-feature="WebXR Device API" data-expires="2018-08-28" content="AnNpu7ceXvLew05ccD8Zr1OZsdZiB2hLQKK82kTTMDwF7oRKtP3QEJ4RzkeHrmB8Sq0vSV6ZNmszpBCZ0I8p9gAAAABceyJvcmlnaW4iOiJodHRwczovL2ltbWVyc2l2ZS13ZWIuZ2l0aHViLmlvOjQ0MyIsImZlYXR1cmUiOiJXZWJYUkRldmljZSIsImV4cGlyeSI6MTUzNTQxNDQwMH0=">

    <title>Framebuffer Scaling</title>

    <link href='css/common.css' rel='stylesheet'></link>

    <!--The polyfill is not needed for browser that have native API support,
        but is linked by these samples for wider compatibility.-->
    <script src='js/xrray-polyfill.js' type='module'></script>
    <script src='js/webxr-polyfill.js'></script>

    <script src='js/webxr-button.js'></script>
  </head>
  <body>
    <header>
      <details open>
        <summary>Framebuffer Scaling</summary>
        <p>
          This sample demonstrates scaling the framebuffer used for a WebXR layer
          at creation time to control the memory and fillrate required and improve
          performance or quality as needed. (The system may clamp the actual
          buffer sizes)

          Framebuffer scaling should be used to make a performance/memory/quality
          tradeoff for the lifetime of the session.
          <a class="back" href="./index.html">Back</a>
          <br/>
          <hr/>
          <input id='framebufferScaleSelect' value='1.0' min='0.25' max='2.0' step='0.125' type='range'/><br/>
          <span id='framebufferScaleLabel'></span>
        </p>
      </details>
    </header>
    <main style='text-align: center;'>
      <p>Click 'Enter XR' to see content</p>
    </main>
    <script type="module">
      import {Scene} from './js/cottontail/src/scenes/scene.js';
      import {Renderer, createWebGLContext} from './js/cottontail/src/core/renderer.js';
      import {Gltf2Node} from './js/cottontail/src/nodes/gltf2.js';
      import {QueryArgs} from './js/cottontail/src/util/query-args.js';
      import {FallbackHelper} from './js/cottontail/src/util/fallback-helper.js';
      import {CubeSeaNode} from './js/cottontail/src/nodes/cube-sea.js';

      // If requested, initialize the WebXR polyfill
      if (QueryArgs.getBool('allowPolyfill', false)) {
        var polyfill = new WebXRPolyfill();
      }

      let scaleSelect = document.getElementById('framebufferScaleSelect');
      let scaleLabel = document.getElementById('framebufferScaleLabel');

      function updateLabel() {
        let value = parseFloat(scaleSelect.value);
        let label = `Framebuffer scale: ${scaleSelect.value}`;
        switch (value) {
          case 0.5: label += ' - 50% recommended res'; break;
          case 1.0: label += ' - Default, system recommendation'; break;
          case 1.5: label += ' - 150% recommended res'; break;
          case 2.0: label += ' - 200% recommended res'; break;
        }
        scaleLabel.innerHTML = label;
      }

      scaleSelect.addEventListener('change', updateLabel);
      updateLabel();

      // XR globals.
      let xrButton = null;
      let xrRefSpace = null;

      // WebGL scene globals.
      let gl = null;
      let renderer = null;
      let scene = new Scene();
      scene.addNode(new CubeSeaNode());

      function initXR() {
        xrButton = new XRDeviceButton({
          onRequestSession: onRequestSession,
          onEndSession: onEndSession,
          supportedSessionTypes: ['immersive-vr']
        });
        document.querySelector('header').appendChild(xrButton.domElement);
      }

      function onRequestSession() {
        navigator.xr.requestSession('immersive-vr').then(onSessionStarted);
      }

      function onSessionStarted(session) {
        session.mode = 'immersive-vr';
        xrButton.setSession(session);

        session.addEventListener('end', onSessionEnded);

        if (!gl) {
          gl = createWebGLContext({
            xrCompatible: true
          });

          // Set up a non-black clear color so that we can see if something renders wrong.
          gl.clearColor(0.1, 0.2, 0.3, 1.0);

          renderer = new Renderer(gl);

          scene.setRenderer(renderer);
          scene.inputRenderer.setControllerMesh(new Gltf2Node({url: '../media/gltf/controller/controller.gltf'}));
        }

        // This is the only meaningful change in this sample from xr-presentation.js.
        // It sets a requested scale to be applied to the framebuffer created
        // for the layer. The UA is allowed to ignore the request or adjust it
        // as needed. The scale of the framebuffer cannot be changed after the
        // layer is created, though the UA is allowed to resize the framebuffer
        // at any time.
        let scale = parseFloat(scaleSelect.value);
        session.updateRenderState({
            baseLayer: new XRWebGLLayer(session, gl, {
              framebufferScaleFactor: scale
            })
        });

        session.requestReferenceSpace('local').then((refSpace) => {
          xrRefSpace = refSpace;

          session.requestAnimationFrame(onXRFrame);
        });
      }

      function onEndSession(session) {
        session.end();
      }

      function onSessionEnded(event) {
        xrButton.setSession(null);
        gl = null;
      }

      function onXRFrame(t, frame) {
        let session = frame.session;
        let pose = frame.getViewerPose(xrRefSpace);

        scene.startFrame();

        session.requestAnimationFrame(onXRFrame);

        scene.updateInputSources(frame, xrRefSpace);

        scene.drawXRFrame(frame, pose);

        scene.endFrame();
      }

      // Start the XR application.
      initXR();
    </script>
  </body>
</html>
